Delivery systems are known in the art and have been widely used for targeted delivery of drugs in the body in the pharmaceutical industry, for example. Delivery systems are also often found in the form of microcapsules for food processing.
In food applications, with the use of delivery systems, possible undesirable interaction between the added nutraceutical and other components in the food or its environment can be avoided and the location of release of the added component can be manipulated. The appropriate application of delivery system technology enables maximization of food without affecting the taste, aroma or texture thereof. It can impart protection to sensitive food ingredients and enhance the shelf-life and stability of fortified foods.
Delivery systems can also be a key technology with potential for the delivery of dietary bioactive compounds and/or cosmetic agents. In addition, the optimum delivery system should also meet the need for site specific delivery within the gastrointestinal tract, or skin, hair etc, depending on the desired application.
For this purpose, microencapsulation has often been used. Indeed, the encapsulation of flavours and other active agents in a matrix of a food polymer is well known.
For example, EP 0 180 441 B1 teaches the use of whey proteins to encapsulate volatile flavour components. Hydrolysed milk is concentrated by heating and evaporation to 40-50% solids which also results in the encapsulation with the whey proteins.
WO 96/38055 describes the encapsulation of a flavour or active agent in a matrix of whey protein yielding an encapsulation composition which results in the controlled release of the flavour or active agent and which may be incorporated in a yeast-leavened dough without causing a deleterious effect on the rising of the dough.
WO 2005/048998 is concerned with gastro-intestinal tract delivery systems, whereby microcapsules made from protein and carbohydrate are used.
One of the problems encountered with the production of products containing globular proteins in general, and whey protein in particular, however is their limited processability. Indeed, protein molecules when heated, or when subjected to acidic or alkaline environment or in the presence of salts tend to lose their native structure and reassemble in various random structures such as gels, for example.
In the Proceedings of the Second International Whey Conference, Chicago, October 1997, reported in International Dairy Federation, 1998, 189-196, Britten M. discusses heat treatments to improve functional properties of whey proteins. A process for producing whey protein micro-particle dispersion at 95° C. is described.
Sato et al. in U.S. Pat. No. 5,882,705 obtained micellar whey protein by heat treating a hydrolysed whey protein solution. The micellar whey protein are characterised by an irregular shape.
The encapsulation systems of the prior art, therefore, have been shown to be poorly effective in the controlled release of a flavour or similar agents, insofar as they partially consist of globular protein and are therefore prone to structural modification upon heating, exposure to salts and/or subjection to acidic or alkaline environment.
Thus, there remains a need for a delivery system composition which enables controlled release of a given agent. In addition, advanced food and cosmetic technology requires particularly designed products, such that the active ingredients contained in the delivery system are protected from environmental stress such as UV radiation, light, oxygen, humidity and temperature.
Accordingly, the object of the present invention is to improve the usability of whey proteins as delivery system in a wide range of applications.